MAGNETIC SURVEY OF A FAULT SPLAY OF THE WILZETTA FAULT IN CENTRAL OKLAHOMA

Earthquakes of magnitude 4.7 and 5.6 affected central Oklahoma in November of 2011. The magnitude 5.6 earthquake injured 2 people, destroyed 14 homes, and buckled parts of Highway 62. A map of foreshocks, aftershocks, and the main earthquake shows a linear array of epicenters that intersect the Wilzetta fault at an oblique angle, suggesting seismic activity along a fault splay. The Wilzetta fault is a northeast trending strike-slip fault approximately 88 km long that was mostly active during the Carboniferous. Seismic data indicates that the earthquakes were located approximately 5 km below the surface. Previous work suggests that the injection wells close to the fault are associated with the seismic activity. This suggests that the fault splay contains fluids, which would result in a high magnetic susceptibility that may be detected with a magnetometer. This project used magnetic exploration to image a possible fault splay throughout the seismically active area of Lincoln County in central Oklahoma. A G-858 Magnetometer was used to acquire continuous high-resolution data along county roads oriented South to North and West to East. A partner with a handheld GPS unit marked locations of magnetic anomalies caused by artificial structures, such as natural gas pipelines and electrical lines. Data analyses involve removing noise from non-geologic bodies, spatially matching the data, and amplification to improve image resolution. Results will characterize the fault splay at depth and will be compared with seismic data to provide new information of a seismically reactivated segment of the Wilzetta fault.